Typically, in a Liquefied Petroleum Injection Engine, the liquefied petroleum is injected into the engine by an injector. Any fuel that is remaining following injection is returned to the fuel cylinder through a return line. The liquefied petroleum has the property of easily evaporating, therefore, a large number of bubbles are easily formed in the fuel returned to the cylinder.
The bubbles cause noise generation when they break in the cylinder and, furthermore, when the returning fuel is falling if the nozzle of the fuel return valve is not immerged in the fuel inside the cylinder. Therefore, it would be advantageous to reduce the noise generated by the bubbles in the fuel.